Indexation in mutual funds reduces tax by adjusting the purchase cost for inflation, where indexation is permitted under current tax laws. It uses the Cost Inflation Index to calculate long-term capital gains. This lowers taxable profit and improves post-tax returns.
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Indexation in mutual funds refers to a change in the purchase price of a given investment to consider inflation. It helps in reducing capital gains that are subject to taxation in eligible long-term investments where indexation is permitted, including debt mutual funds purchased before 1 April 2023. When the investment is long-term, the price of purchase under the Cost Inflation Index is indexed, and thus, the taxes payable are reduced. This made certain long-term debt fund investments more tax-efficient under earlier tax rules.
The Cost Inflation Index (CII), notified by the Ministry of Finance, is used to calculate indexation by adjusting the original purchase cost for inflation. Accordingly, the indexed cost is applied to compute long-term capital gains, which helps reduce taxable profit and lower the tax liability on debt funds.
Formula:
Indexed Cost = (CII in the year of sale ÷ CII in the year of purchase) × Purchase Price
The following example applies to investments that qualify for indexation benefits under the tax laws applicable at the time of purchase.
Example:
Assume that an investor invests in units of mutual funds worth ₹10,000 in the financial year 2018-19 and sells them in 2021-22 at ₹15,000. In the absence of indexation, the capital gain that is subject to tax is ₹5,000.
Suppose the Cost Inflation Index is 280 in 2018-19 and 320 in 2021-22.
Indexed Cost = 10,000 × (320 ÷ 280)
= 10,000 × 1.142857
= ₹11,428.57
Taxable gain = ₹15,000 − 11,428.57 = ₹3,571.43
This shows how indexation reduces tax liability.
Indexation is significant in improving tax efficiency for eligible long-term mutual fund investments, including certain debt funds purchased before 1 April 2023. Inflation adjustment on purchase cost minimises taxable capital gains and enhances post-tax returns. It aims to tax gains after adjusting the purchase cost for inflation. This renders indexation a very useful attribute to individuals who desire to construct a consistent and economical long duration investment.

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^^The information relating to mutual funds presented in this article is for educational purpose only and is not meant for sale. Investment is subject to market risks and the risk is borne by the investor. Please consult your financial advisor before planning your investments.